Tessa Geelen1, Sin Yuin Yeo1, Leonie E. Paulis1, Bram F. Coolen1, Klaas Nicolay1, Gustav J. Strijkers1
NMR, Department of Biomedical Engineering,
After a myocardial infarction, macrophages infiltrate the damaged tissue to remove dead cells and promote left ventricular remodeling. The aim of this study was to characterize the presence of these macrophages with MRI. Phosphatidylserine (PS) was incorporated in paramagnetic liposomes to promote uptake by macrophages. In vitro, liposomes containing 6 mol% PS showed the highest uptake by murine macrophages. These liposomes were applied after mouse cardiac ischemia/reperfusion injury and visualized with T1-weighted MRI and confocal microscopy. PS-liposomes were specifically associated with macrophages in the infarcted myocardium 2.5 hours after injection. After 24 hours of circulation, passive accumulation was predominant.